Combined time-temperature switch device



J. L. HARRIS COMBINED TIME-TEMPERATURE SWITCH DEVICE June 28, 1966 5Sheets-Sheet 1 Filed March 4, 1963 yJune 28, 1966 J. l.. HARRIS3,258,552

COMBINED TIME-TEMPERATURE SWITCH DEVICE Filed March 4, 1963 5Sheets-Sheet 2 June 28, 1966 J. L. HARRIS COMBINED TIME-TEMPERATURESWITCH DEVICE 5 Sheets-Sheet 5 Filed March 4, 1963 Mv/mlwa June Z8, 1966J. L. HARRIS 3,258,552

COMBINED TIME-TEMPERATURE SWITCH DEVICE Filed March 4, 1963 5Sheets-Sheet 4 J. L. HARRIS COMBINED TIME-TEMPERATURE SWITCH DEVICE June28, 1966 5 Sheets-Sheet 5 Filed March 4, 1963 United States Patent O3,258,552 COMBINED TIME-TEMPERATURE SWITCH DEVICE John L. Harris,Whitefish Bay, Wis., assiguor to Miller- Harrs Instrument Company,Milwaukee, Wis., a corporation of Wisconsin Filed Mar. 4, 1963, Ser. No.262,471 20 Claims. (Cl. 200-39) This invention relates to automaticcontrols and more particularly to time controls for automatic defrostingof frozen food cabinets and other purposes.

The primary object of the invention is to provide a dependable compactunit of simple and heavy duty construction, and which is quick and easyto set, both for time and duration of defrost cycles.

A further lobject is to provide a basic timer unit which is capable ofboth starting and terminating a cycle, and which is constructed so thatan accessory cut-off unit such as a solenoid or pressure responsive unitcan readily be added or omitted.

Another object of the invention is to provide a pressure cut-olf unit inwhich the same spring can be used for a number of different pressureranges.

Other objects will appear from the following description and appendedclaims.

For a full disclosure of the invention, reference is made to thefollowing detailed description and to the accompanying drawings inwhich:

FIG. 1 is a front view of the improved defrost control;

FIG. 2 is a side view of FIG. l;

FIG. 3 is a fragmentary view in which the dial is broken away toindicate the operation of the trip lever by the dial trip pins.

FIG. 4 is a view corresponding to FIG. 3 but behind the timer frontplate, showing the operation of the trip lever for starting a cycle;

FIG. Sis a schematic view of the gear train;

FIG. 6 is a view similar to FIG. 1 in which the front panel is omittedto show the switch operating mechanism in the normal or run position;

FIG. 7 is a sectional view taken on line 7-7 of FIG. 6;

FIG. 8 is a partial View similar to FIG. 6 but showing lthe positionsassumed by the parts during the defrost cycle and just before thetermination thereof;

FIG. 9 is a view similar to FIG. 8 but showing the parts just after thetermination of a defrost cycle;

FIG. 10 is a front view with parts omitted to illustrate the gear trainand cam shaft assemblies;

FIG. ll is a sectional view taken on line 11--11 of FIG. 10;

FIG. 12 is a broken away perspective view of the dial assemblyillustrating the trip pin and spring construction;

FIG. 13 is a detail view of the spring and trip pin;

FIG. 14 is a view similar to FIG. 6 but illustrating the addition of apressure cut-off accessory;

FIG. l is a side view of FIG. 14;

FIG. 16 is a perspective view of the pressure cut-olf accessory;

FIG. 17 is a view similar to FIG. 14 but showing the addition of asolenoid cut-off accessory;

FIG. 18 is a side view of FIG. 17 partly in section;

FIG. 19 is a perspective view of the solenoid cut-off accessory.

Referring particularly to FIGS. 1, 2, 14 and l5, a base member 1 isformed as a channel having side members 2 and 3. The base member also isprovided with inturned portions 4 and 5 at the top and bottomrespectively. These portions 4 and 5 serve to mount the base on amounting bracket 6 as shown in FIG. 2. A switch panel 7 of phenolicmaterial is mounted on the upper portion of the base member 1. As shownin FIGS. 2 and lCe 10 this switch panel 7 rests directly on the channelmembers 2 and 3 of the base member and is provided with ears A8 whichextend into slots in the upper inturned section 4 of the base member. Asshown in FIG. 14 and also in FIG. 7, the base member 1 is provided witha large opening 10 behind the switch panel. This opening provideselectrical clearance for the switches 11 and 12 which are mounted behindthe switch panel 7. The switch 11 is illustrated as of the double throwvariety and includes a switch blade 13 which is carried on a bracket 14and which extends Ibetween contact brackets 15 and 16. The switch 12consists of a switch blade 17 carried by a bracket 18, this switch bladecarrying a contact which cooperates with a contact carried by thecontact bracket 19. In order to conserve space the switch blades 13 and17 are formed L shaped which permits the switch blade brackets 14 and 18to be mounted in a horizontal plane.

The switch blade brackets and contact brackets are of identical L shapedconstruction, one leg serving to hold the switch blade or bracket, andthe other leg 21 fitting flat against the switch panel as shown in FIG.7. This leg 21 is provided with a tapped hole f-or receiving a terminalscrew 22. This portion 21 of the bracket is fastened to the bracket bymeans of a terminal plate 23 which is generally Ushaped, having legportions 24 which extend into suitable slots in the switch or contactbrackets. These leg portions 24 in extending through the panel and intothe switch or contact bracket prevent turning or twisting of thesebrackets on the panel. In addition the leg portions 24 are crimped overas shown in FIG. 7 which provides a rigid fastening and also insuresgood electrical contact between the terminal plate 23 and the bracket.

As shown in FIGS. 6 and 7 the switch blades 13 and 17 extend downwardlypast the contact brackets. Both of these switch blades are biased to theright as seen in FIG. 6. They are moved against their bias by means of acommon sliding switch operator 27. This switch operator is made ofinsulating material and carries pins 28 and 29 which operate the blades13 and 17, respectively. The construction of this switch operator isshown more clearly in FIG. 14. This operator is provided with a pair ofslots 30 and 31 which ride over studs 32 and 33 mounted on the basemember 1. As shown in FIGS. 7 and l5 the switch operator 27 is locatedadjacent the base member 1 and is held in place -by means of enlargedportions 35 on the studs 32 and 33. As shown in FIG. 7, the studs arestaked into the base member 1 and thus serve to lock the switch operator27 to the Ibase but in slideable relationship therewith. It will benoted that substantial portions of the switch operator extend above andbelow the studs 32 and 33. This prevents rocking motion of the switchoperator on the base plate but still permits the switch operator toslide to the left or right on the base member for operating the switchblades.

Mounted in front of the switch operator 27 is an elongated sliding camfollower 38. As shown in FIGS. 6 and 7 this cam follower is formed withslots 39 and 40 which tit over studs 32 and 33 respectively. As shown inFIG. 7 the cam follower 38 rides over reduced portions of the studs 32and 33 and thus the enlarged portions 35 of these studs serve to spacethe cam follower 38 from the switch operator 27. As shown in FIG. 7, theterminal panel 7 also fits over reduced portions 41 of the studs 32 and33. This reduced portion 41 of each stud maintains a space between theterminal panel and the cam follower so that the cam follower is free toslide.

The cam follower 38 is provided with a stud 43 which has a Iforwardlyextending portion which carries a biasing spring 44. This biasing springis shown as a tension spring and its other end is secured to a stud 45carried on aaeaase the base member 1. This biasing spring 44 biases theca-m follower 38 to the right as seen in FIG. 6.

The stud 43 also has a rearwardly extending portion 46 which carries apawl 47. This pawl 47 is located adjacent the base plate 1 in the sameplane with the switch operator 27. As shown more clearly in FIG. 8 thebase member 1 is formed with a forwardly extending tab 49. This tab 49constitutes a stationary abutment which the pawl 47 engages when thedefrost control is in the normal position as shown in FIGS. 1 and 6. Theswitch operator 27 is also formed with an abutment 50 which is adjacentto the tab 49 as shown in FIG. 6 when the control is in the normalposition. The switch operator 27 also carries a spring stud 52 whichextends through a suitable opening in the cam follower 38. This springstud 52 is attached to a spring S3 which in turn is secured to a stud 54attached to the base member 1.

With the parts in the positions shown in FIG. 6 the spring S3 is biasingthe switch operator 27 toward the left. The pins 28 and 29 on thisswitch operator thus urge the switch blades to the left as shown. Thespring 44 is biasing the cam follower 38 to the right and the camfollower is held in the position shown by the pawl 47 engaging thestationary abutment 49 on the base member 1.

The cam follower 38 is formed with a cam follower portion 55 which ridesa reset cam 56. Preferably a guide 57 is mounted on the base 1 and isslotted to receive the lower edge of the cam -follower 38. This preventsrocking motion of the cam follower and insures that the cam followerproperly rides the cam 56.

The cam 56 is carried by a cam shaft along with a starting cam 58. Asshown in FIG. ll, the cam shaft 57 which carries cams 56 and 58 ishollow and receives a second cam shaft 59. This cam shaft 57 alsoextends through a hub 61 which is free to rotate in a front bracket 62.This front bracket at its lower end is supported on base 1 by means ofspacers 63 and 64. This bracket at its upper end is offset as at 65 andhas a portion 66 which covers the lower end of the terminal panel 7.This portion of the front bracket is maintained in place by means ofscrews 67 which are threaded into the studs 32 and 33 which also supportthe switch operator 27 and the cam follower 38. The cam shaft 57 at itsfront end carries a pointer 70 which carries a projection 71 which isadapted to fit into a series of slots 72 of the defrost adjusting dial73. The sha-ft 59 is formed with a reduced section 75 at the rear endthereof and carries a bearing member 76 which is fitted into an openingin the back plate 1. This bearing member carries a stopping cam 77 whichis adjacent the back plate 1. A compression spring 7S fits over thereduced portion 75 of the shaft 59 and pushes on the bearing member 76so as to bias the inner shaft 59 rearwardly with relation to the outershaft 57. This permits the user to change the defrost timing by pullingthe dial 73 outwardly far enough to clear the projection 71 on thepointer 70. The dial is then turned to the desired defrost timing andreleased Vat which time the spring 78 pulls the dial '73 back intoengagement with the projection 71 in its new setting. This turning ofthe dial 73 changes the position of the off cam 77 relative to thestarting cam 58.

The hub 61 fits over the shaft 57 and serves as a bearing for the frontend of the cam shaft assembly in the front bracket 62. This hub 61carries a twenty-four hour dial assembly generally indicated as 81. Thisdial assembly includes a cup shaped dial or knob member 82 which isprovided with a series of radial extending slots 83 receiving trip pins84. As shown in FIG. 1, a separate slot and trip pin are provided foreach two hour period of the day. Also as shown in FIG. 1 the dial 81 isprovided with suitable indicia for indicating the hours of a twentyfourhour one day period. This indicia on the dial cooperates with a Timearrow 85 which is carried on a cover plate 86. This cover plate 86 ismounted on the front bracket 62 Aby means of screws 87 and is formedwith a large hole 88 for clearing the knob 82. This cover plate 86 ismade of insulation material and in addition to carrying the Time arrowalso protects the user from the electrical connections on the switchpanel.

As shown in FIG. ll the di-al assembly also includes a retainer plate 89which carries a series of slots 90 which are identical with the slots 83in dial 82. The dial 82 and the retainer plate 89 are suitably staked tothe hub 61 and are offset relative to each other so as to provide aspace 91 between these parts and adjacent the slots. This space 91receives enlarged portions 92 of the trip pins 84. Each trip pin 84includes a rearwardly extending portion 93 for engaging a trip lever 94which is carried on the front bracket 62 (FIG. 3). This trip lever 94 ispivotly mounted on the front bracket 62 closely adjacent to this bracketand includes an outturned portion which is adapted to be engaged by therear portions 93 of the pins 84. When a pin 84 is in its outer positionit will engage the trip lever outturned portion 95 and rotate the triplever 94 in a clockwise direction as the pin passes over the trip lever.However, when a pin 34 is located in its inner position, the pin willmiss the outturned portion 95 of the trip lever and no movement of thistrip lever will take place when such a pin passes by. Thus the pins whenlocated at the outer edges of their slots serve to start a defrost cycleat the time indicated. However, the pins at the inner ends of theirslots are inactive and will not start a defrost cycle.

The space 91 between the dial member 82 and the retainer plate 89 ismade slightly larger than the width of the enlarged portions 92 of thepins 84 so that these p'ns slide freely in their slots. These pins areheld at one end or the other by individual springs 96. As shown in FIG.ll the retainer plate 89 is formed with a series of extrusions 97, onefor each slot 90. The springs 96 are of the torsion type having a woundportion 98 which fits over the extrusions 97. The legs of each springare formed as shown in FIGS. 12 and 13 to provide camming surfaces 99and 100. These camming surfaces engage the enlarged portions 92 pins 84.Preferably the pin 84 is dished as shown in FIGS. l1, l2 and 13 so as toprovide a track for retaining the spring in place. It will be apparentthat when a pin 84- is at the outer end of its slot, the camming surface100 of the spring serves to push the pin ltowards this end of the slot.When a pin 54 is moved from its outer end of its slot the cammingsurfaces 100 of the spring causes the spring to open up. When the pinpasses from the camming surface 100 to the camming surface 99 of thespring, the spring now serves to cam the pin inwardly and hold the pinagainst the inner edge of its slot. This arrangement makes it easy forthe user to set the pins for the desired defrost `cycles and alsoinsures that the pins will stay either at one end or the other of theirslots.

Referring again to FIGS. 2 and ll, the hub 61 which carries thetwenty-four-hour dial assembly 81 is driven by a gear 161 through afriction drive including a tension washer 192 and a retainer 103. Theouter cam shaft 57 which carries the reset cam 56 and the starter cam 58is driven by a gear 164 which is rigidly secured to this cam shaft. Atimer motor 19S (FIG. 2) is mounted at the rear of the base member 1below the switches and serves to drive both gears 161 and 194 through agear train, the details of which are shown in FIG. 5. The timer motorincludes a pinion 1116 which drives gear 107 which in turn drives gear108. This gear 168 drives the gear 164 through a gear 109 and a pinion110 which meshes with the mutilated gear 104. The pinion of gear 198also meshes with a gear 111 which drives the gear 101 through gear andpinion 112. It will be noted that the cam shaft gear 164 is driven bythe timer motor through a gear reduction of four gears whereas thetwenty-four hour gear 191 is driven by the same timer motor through agear reduction including tive gears. The gear 101 is thus a slow speedgear and the gear reduction is selected to cause,

rotation of the dial assembly one revolution in Itwentyfour hours and ina clockwise direction. The gear 104 is a high speed gear for the camshaft and serves to drive the cam shaft in a counterclockwise direction.In the ernbodiment illustrated the gear reduction for the cam shaftserves to drive the cam shaft in a counterclockwise direction at a speedof one revolution in three hours.

The gear 104 which drives the cam shaft 57 is of the mutilated typeincluding a portion 114 in which the teeth are omitted. (See FIG. 3.)This gear carries a starter pin 115 which is adapted to be engaged by apawl 116 which is riveted to a lever 117 carried on shaft 118. Thisshaft 118 extends through the front bracket 62 and carries the startinglever as shown in FIG. 3.

Referring now to FIGS. 6 and 7 a starter cam follower 120 is mounted ona stud 121 carried by the base member 1 and in alignment with thestarter cam 58. This cam follower 120 is provided with a torsion spring122 which urges it into engagement with the starter cam 58. This cam 58carries a starting pin 123 which is adapted to engage the lower surface124 of the pawl 47.

Operation of timer unit FIGS. 3, 4 and 6 show the parts in the positionsassumed when the defrost unit is in the normal or run position and justbefore a new defrost cycle is to be initiated. Referring to FIG. 6 inparticular, the cam follower 38 has been cammed to the left by the resetcam 56 to a point at which the pawl 47 is behind the stationary abutment49. A 4this point the toothless section 114 of the gear 104 has becomeadjacent to the pinion 110. As a result, the pinion 110 is incapable ofrotating the gear 104 and the cam shaft 57 is stationary with its timeindicator 71 in an upright position as shown in FIGS. l and ll. At thispoint, the cam follower portion 55 of the cam follower 38 has disengagedthe reset cam 56 and the cam follower is prevented from moving to theright as seen in FIG. 6 due to the pawl 47 engaging the stationaryabutment 49. The pressure of the spring 44 is thus carried by the pawl47 and thus exerts no influence on the cam shaft at this time. Thespring 53 has pulled the switch operator to the left and the pins 28 and29 of this operator have moved switch blades 13 and 17 to the positionsshown. Thus a compressor circuit is closed between terminal brackets 14and 16. The circuits are opened between brackets 14 and 15 and alsobetween brackets 18 and 19.

As the 24-hour dial rotates clockwise and as shown in FIG. 3, the innerend 93 of a trip pin engages the turned up portion 95 of the trip lever94. This rotates the trip lever shaft 118 in a clockwise direction whichin turn rotates the lever 117, causing the pawl 116 to approach thestarting pin 115 which is carried by gear 104. The 24-hour dial is thusserving to start rotation of the cam shaft 57 in a counte-r clockwisedirection.

Referring to FIG. 6 this rotation of the cam shaft 57 brings the abruptdrop olf portion of the starter cam 58 under the starter cam follower120. The pressure of the starter cam follower on this portion of the cam58 causes a snap action counter-clockwise rotation of the cam shaft forbringing gear 104 back into engagement with the pinion 110. At this timethe starter pin 123 carried by the starter cam has not contacted thelower portion 124 of the pawl 47. The pressure of the starter camfollower 120 on the starter cam feeds the gear 104 into mesh with thepinion 110, and the pinion 110 now begins to drive the gear 104 counterclockwise for one revolution independently of the starter cam follower120.

4right-hand end of pawl `47 moves downwardly relative to the stationaryabutment 49. The pawl 47 now rides off the lower edge of the abutment 49and the spring 44 becomes free to pull the sliding cam follower 38 tothe right. At this time the pawl 47 engages the abutment 50 of thesliding switch operator 27. The spring 44 is stronger than the switchoperator spring 53 and thus the switch operator is pulled to the rightalong with the cam follower. This permits the switch blades 13 and 17 tomove to the right for breaking the circuit between brackets 14 and 16and making circuits between brackets 14 and 15 and between brackets 18and 19. The defrost cycle is now underway.

It should be noted .that the parts are proportioned so that the lowersurface 124 of the pawl 47 is substantially horizontal at the time thatthe pawl 47 disengages the stationary abutment 49. The pawl thus is freeto slide relative to the starting pin 123 Without disengaging theabutment 50 of the switch operator. It should also be noted that thismovement of the pawl 47 along with the cam follower moves the pawl awayfrom the starting pin 123. As a result, the starting pin 123 no longerhas any effect on the pawl and passes clear of the pawl as the cam shaftrotates.

As shown in FIG. 6 the cam follower 38 is provided with an opening 128through which passes a stud 129, this stud being attached to the basemember 1 similarly to the studs 32 and 33. The left-hand end of theopening 128 serves as a stop for limiting the motion ofthe cam follower38 by spring 44. Thus when the parts are in the defrost position, thelocation of the cam follower 38 and hence the location of the pawl 47are definitely predetermined.

As the cam shaft continues to rotate, the stopping cam 73 approaches thelower surface 124 of the pawl 47 as shown in FIG. 8. This stopping camon continued rotation rotates the pawl 47 counterclockwise to a point atwhich its end clears the abutment 50 as shown in FIG. 9. The spring 53for the switch operator is now free to pull the switch operator to theleft for returning the switches to the positions shown in FIG. 6. Thedefrost cycle has now 'been terminated.

After the cam shaft has been driven to a point slightly beyond themaximum defrost time adjustment, the timer starts its reset phase. Atthis time the rise portion of the reset cam 56 engages the cam followerand moves the follower to the left thus stretching the spring 44. Theparts are proportioned so that the cam 56 moves the cam follower to theleft sufficiently to provide a gap between the pawl 47 and thestationary abutment 49. The biasing spring for the pawl 47 now causesthe pawl to drop behind the stationary abutment. The cam 56 then clearsthe cam follower and the cam follower moves slightly to the right and isstopped by the pawl 47 engaging abutment 49. After this has taken place,the cam shaft is stopped due to the teeth of gear 104 running olf thepinion 110.

It should -be noted that in this position, an intermediate level -of thecam 56 is still under the cam follower. This portion is low enough to beclear of the cam follower when the pawl 47 is in engagement with thestationary abutment 49. However, if for some reason the latch 47 failedto engage the stationary abutment, this intermediate portion of cam 56will prevent the control unit from accidentally getting into a defrostcycle. If the pawl 47 should fail to engage the abutment 49, thepressure of the cam follower spring will now be carried by the reset cam56. This will greatly increase the torque required for starting the camshaft into a defrost cycle. Preferably, the friction drive of the dialassembly 81 is set up for insuicient torque to start a cycle under theseconditions. Thus if the pawl fails to operate properly, the control unitwill fail in a safe position. Y Y

It should also be noted that the invention provides' a unit in which thetimer motor will always fail in a safe position. At the time a defrostcycle is started the spring 44 is the one which applies pressure of thepawl 47 against abutment 49. At the termination of a defrost cycle thespring 53 is the one which applies pressure on the pawl 47 through theabutment. inasmuch as spring 44 is stronger than spring 53 it followsthat the pressure on the pawl at the start of a defrost cycle is greaterthan the pressure on -the pawl at the termination of a cycle. Thus moretorque is required of the timer motor to start a cycle than to terminateit. It is a characteristic of timer motors to gradually diminish intorque output with age. This is a slow process. Thus if the motor hassuticient torque to start a cycle, it will always have enough torque toterminate it.

It should also be noted that the construction described requires nopower from the timer motor during a defrost cycle except that requiredto release the pawl 47 from the switch operator abutment 50. After thishas taken place with the unit adjusted for maximum timing, the resetcycle is started in which the cam follower is camrned to the left forstretching spring 44. If a timer motor is going to fail it will usuallyfail during this reset portion of the cycle. This is further insuranceagainst a motor failure during a defrost cycle.

Another feature provided by the invention is the provision for startingextra defrost cycles without disturbing the automatic set-up. This isdone simply by ilicking the defrost dial 73 in a counterclockwisedirection manually. This has the same effect as starting a cycle by thedefrost pins. In addition, the unit may be turned manually through acomplete defrost cycle for testing and without disturbing the 24 hourdial setting. This is provided for by the one Way drive arrangementdisclosed. As shown in FIG. the gear 109 and pinion 110 which drive thecam shaft gear 104 are carried on a shaft 130 which extends between thefront bracket 62 and the base plate 1. The front end of the shaft 130extends into a slot 131 in the front bracket (FIGS. 4 and 10). A biasingspring 132 is provided for urging the shaft in a direction for bringingthe pinion 110 into engagement with the gear 104. When the cam shaft isturned counterclockwise manually, it moves the pinion 110 to the rightagainst the tension of the spring 132. This gives a ratcheting effectand permits easy rotation of the cam shaft in its normal direction.However, the reaction of the pinion 110 in driving the gear 104 pullsthe pinion into further engagement with the gear and thus a positivedrive is provided by the timing mechanism.

From the foregoing description it will be apparent that the presentinvention provides a simple compact unit which may `be readily adjustedby the user for the defrost sequence required. The times that defrostcycles are to start Iare instantly set simply by flicking theappropriate trip pins on the dial in or out. The duration of a cycle iseasily and quickly set simply by pulling out the defrost dial, settingit to the desired timing and releasing it. In addition, the user iscompletely protected from danger of electric shock during such setting.Also, the timing accuracy of the defrost cycle is improved by thearrangement in which a single pawl serves to both start and terminate acycle.

T zme pressure control The invention thus far described is a basic unitin which a defrost cycle is started by the timer and in which the timeris the sole means for terminating such cycle. Another requirement in theindustry is for a unit which starts a defrost cycle by a timer and whichterminates such cycle in response to a pressure rise in the system. Insuch units, the time termination feature is still retained as a failsafe feature in the event the pressure cut off fails for some reason tooperate.

The present invention provides for the conversion of a basic time cutolf unit to a time pressure unit simply by adding a pressure controlaccessory and this feature of the invention is shown in FIGS. 14, and16.

This pressure cut-olf accessory includes a base member generallyindicated as 135 which is attached to the rear of the timer base member1 by screws at 136 and 137. As shown in FIGS. 15 and 16 this base memberis generally U-shaped. One leg 138 is parallel with the base member 1and is secured to the base member by the screws 136 and 137. Theintermediate portion 139 of base member extends rearwardly and carries abellows assembly 140 including an operating pin 141. The rear portion142 of the base member extends upwardly serving to strengthen the basemember and also to provide a support 143 for the pressure 4control levergenerally indicated as 144. As shown in FIG. 16, this pressure controllever is channel shaped having an intermediate portion 145 and sideportions 146 and 147. The side portion 147 is pivoted to the bearingmember 143 as shown in FIGS. l5 and 16. The side member 146 is providedwith a similar and aligned bearing 147 in the main section 138 of thebase member 135. The pressure control lever 144 is also provided with aninturned portion 148 which extends over the operating pin 141 of thebellows assembly 140. Preferably this lever is provided with a dimple150 into which the point of the bellows pin 141 fits. It will be notedthat the point of contact of the pin 141 with the pressure control leveris in substantial alignment with the bearings of this lever.

This side section 146 of the pressure control lever is struck out toprovide a tab 150 which extends through an opening 151 in the basemember 135. As shown in FIG. 14 a corresponding opening 152 is providedin the timer base member 1. The vtab 150 extends through both openingsinto alignment with a side portion 153 of pawl 47.

As shown in FIG. 16 the pressure control lever is biased by means of atension spring 155. This tension spring serves to bias the pressurecontrol lever in a clockwis'e direction as seen in FIG. 14 and urge thetab 150 against the right-hand edges of the openings 151 and 152.

When the pressure in the refrigeration system is below a set value therewill be clearance as shown between the tab 150 and the portion 153 ofthe pawl 47. As the pressure in the system increases, the bellowsassembly 140 will overcome the biasing spring 155 and will move thepressure control lever 146 counterclockwise as seen in FIG. 14. Thiswill cause the tab 150 to engage the pawl 47 and then rotate th'e pawlclockwise for releasing from the abutment 50 of the switch operator.This terminates the defrost cycle in exactly the same way that it wouldbe terminated by the olf cam 77 of the timer mechanism. Thus theinvention provides for operation of the pawl to terminate a defrostcycle by two completely independent means. The defrost cycle may beterminated by either the expiration of a predetermined time or the risein pressure to a predetermined value whichever happens tirst.

Provision is made for adjusting the tension of the spring 155 from thefront of the timer. The other end of the spring 155 is attached to aspring lever 156 which is pivoted in a vertical plane to the pressurecontrol base member 135. The upper end of the base member 135 is formedover as end 158. Also a corresponding tab 159 is struck out from therear section 138 of the base member. For purpose of rigidity theadjusting lever 156 is formed as a box and the upper and lower edges areprovided with holes through which extends a pin 161. The adjusting lever156 at its bottom is formed with a downwardly extending portion 162which is engaged by an adjusting screw 163 which is threaded into thebase member 135. This adjusting screw extends through an opening 164 inthe timer base member 1. A corresponding access opening (not shown) isincluded in the front brackets 62 of the complete timer so that thescrew 163 may be turned for setting the cut-out pressure.

It will be apparent that turning the set screw 163 in will rotate theadjsting leved 156 in a counterclockwise direction as seen in FIG. 16.This will increase the tension of the spring 155 and thus increase thecut-out pressure.

The invention also provides for a unit with a wide range of cut outpressures with exactly the same parts. As shown in FIG. 16 the pressurecontrol iever is provided with a series of holes 165 for receiving thespring 155. The adjusting lever 156 is provided with a similar series ofspring receiving holes 166. As indicated in FIG. 14 the pressure controllever is substantially horizontal at the time that it causes the pawl 47to release from the switch operator abutment 50. In other words, thepressure control lever is in a substantially vertical position at thecut-out point. The pivot for the adjusting lever is also vertical andthus at the cut-out point, the pressure control lever and the adjustinglever are substantially parallel. This means that regardless which setsof holes are used for retaining the spring 15S, the elongation of thespring 155 will be the same at the cut-out point.

It will be noted that the leverage of the tension spring 155 on thepressure control lever is dependent upon the distance the spring is awayfrom the pivot of the lever. Thus if the spring `155 is attached to theuppermost set of holes, the leverage of the spring will be at a maximumand the pressure control unit will be set up for a maximum pressurecontrol range. Conversely if the spring is attached to the lowermost-set of holes, theleverage of the spring will be at a minimum and theunit will be set up for a minimum pressure range.

From the foregoing, it will be apparent that the present inventionprovides a unitary pressure control accessory which may be added to thetimer for converting the timer vto a time pressure type of unit.Furthermore, the invention lprovides for ready adjustment of thepressure cut-out point and also makes it possible for the same accessoryto be used over a wide range of pressure cut-out values.

Time temperature control The present invention also provides forterminating a ldefrost cycle in response to temperature from a remotepoint. For this purpose a solenoid cut-out accessory is added to thebasic timer unit instead of the pressure control accessory as describedabove.

This arrangement is shown in FIGS. 17, 18 and 19. The pressure controlaccessory includes an L-shaped base member generally indicated 'as 170.This base member has one leg 171 which mounts on the timer basemember 1. The base member 170 also includes a leg 172 to which the frame173 of a solenoid generally indicated as 174 is attached. This solenoidincludes a plunger 175 and a biasing spring 176. This solenoid operatesva lever 177 which is carried by a hollow bearing member 178 mounted ona stud 179 carried by the portion 171 of the base member 170.

The lever 177 carries a stud 180 which extends through an opening 181 inthe base member 170. This stud also extends through the opening 152 inthe timer base member 1 and operates the pawl 47.

When the solenoid is de-energizeld the part-s assume the positions shownin FIG. 17 in which the pin 180 is disengaged from the pawl 47 However,when the solenoid is energized, the plunger 174 moves downwardly forcausing a counterclockwise rotation of the lever 177 as seen in FIG. 19.This causes a movement of the stud 180 to the left as seen in FIG. 17which disengages the pawl 47 from the abutment 50 of the switch operator27.

It will be understood that the solenoid in this embodiment of theinvention will be controlled by a thermostat which indicates the systemhas been defrosted. In this embodiment of the invention one switch maybe omitted from the switch panel and space on the panel may be used formaking electrical connections with the timer motor and solenoid. Thedetails of defrost control circuits using a solenoid cut-out are wellknown in the art and consequently are not described or shown in detail.

From the foregoing description, it will be seen that the presentinvention provides a basic defnos-t timer having a number of newfeatures and advantages over prior art devices. The basic timer issimple in construction and is easy and quickly set up for any givendefrost sequence. It protects the user from electric shock and includesbuilt in safety features to prevent a timer failure during the defrostcycle. In addition, it Iprovides for addition of extra cut-off.accessories which may be added to or taken from any given unit withoutimpairing or requiring modification thereof. This provides for economiesin manufacturing as the basic units may be made up by the manufacturerwithout regard as to whether they are to be plain timers or combinationunits. It also simplifies .and reduces inventory requirements in thefield as units c-an be readily converted from one type to another.

While the invention shown and described has particular utility indefrosting applications, it is not limited to the defroster field. Thesame basic mechanisms may be used in a wide number of otherapplications. Also while preferred forms of construction and design havebeen shown and described, it will be apparent that many moditicationsmay be made without departing from the spirit and scope of theinvention. It is, therefore, desired to be limited only by the scope ofthe appended claims.

What is claimed is:

1. In a control device, =a movable member, means biasing said member inone direction, a pawl carried by said movable member, a stationaryabutment in the path of the said pawl, drive means for moving saidmovable member to Ia point where the pawl engages said stationaryabutment and then releasing the movable member so that the movablemember is held against its bias by the pawl engaging said stationaryabutment, Ia control member, means biasing said control member in thedirection opposite to the bias of the movable member but to a lesserdegree, fan abutment carried by the control member also 'in the path ofsaid pawl and engaged thereby after its release Ifrom the stationaryabutment, and means releasing the pawl iirst from the stationaryabutment and then from the control member abutment whereby the controlmember is first moved against its bias to one position and is then movedby its bias to another position.

2. In a control device, a movable member, being means biasing .saidmember in one direction, a pawl carried by said movable member, astationary abutment in the path of the said pawl, drive means for movingsaid movable member to a point where the pawl engages said stationaryabutment and then releasing the movable member so that the movablemember is held against its bias by the pawl engaging said stationaryabutment, a control member, means biasing said control member in thedirection opposite to the movable member but to a lesser degree, anabutment carried by the control member also in the path of said pawl andenga-ged thereby after its release -from the stationary abutment, afirst `operating means arranged to release the paiwl fro-m thestationary abutment whereby the movable member moves the control memberagainst its bias, a second operating means arranged to release the pawlfrom the control member abutment, said rst and second operating meansbeing spaced apart and arranged so that the pawl upon release from thestationary abutment moves away from the first operating means and towardsaid second operating means.

3. In a control device, a cam, a cam follower, means biasing the camfollower toward said cam, a paw-l carried by said cam follower, astationary abutment in the path of said pawl, said cam being arranged tomove the cam follower to a point where the pawl engages the stationaryabutment and to then release the cam follower so that the cam followeris held against its bias by the pawl en gaging said stationaryalbut-ment, a switch operator, means biasing the switch operator in thedirection opposite to the bias of the cam follower but to a lesserdegree, an abutment carried by the switch operator also in the path Yo-fsaid pawl and engaged thereby after its release from the stationaryabutment, and means releasing the pawl first from the stationaryabutment and then from the switch operator abutment, whereby the switchoperator is first moved against `its bias to one position and is thenmoved by its bias to another position.

4. In a timing device, a timing motor, a cam driven by said motor, a camfollower, means biasing the cam follower toward said cam, a pawl carriedby said cam follower, a stationary abutment in the path of the pawl,said cam being arranged to -move the cam follower to a position in whichthe pawl in is engaging relationship with the stationary abutment andthen release the cam follower so that it is held against its bias bysaid pawl, a control member, means biasing the control member in adirection opposite to that of the cam follower but to a lesser degree, asecond abutment carried by said control member also in the path of thepawl and adjacent said stationary abutment, means driven by said timermotor for releasing said pawl from the stationary abutment, said pawlbeing arranged to now engage the second abutment for moving the controlmember with the cam follower, and means releasing the pawl from thesecond abutment for permitting said control member to return to itsinitial position.

5. In a timing device, a cam shaft, a cam carried by said shaft, a gearon said shaft in fixed relationship with said cam, said gear having aportion without teeth, a pinion meshing ywith said gear for driving thesame, a cam `follower biased toward said cam, a pawl carried by said camfollower, a stationary abutment in the path of said pawl, said cam beingarranged to move the cam follower to a position in which the pawl is inengaging relationship with the stationary abutment and then to releasethe cam follower so that it is now held by the pawl, whereby thepressure of the cam follower is removed frorn the cam, said gear beingarranged to disengage the pinion so that 4the cam shaft stops, meansadvancing said cam shaft to re-engage the gear with the pinion, meansoperated by said cam shaft for releasing the pawl from the stationaryabutment, a control member biased in a direction opposite to the camfollower, a second abutment carried by the control member arranged inthe path of said pawl and engaged thereby after its release from saidstationary abutment, and means operated by said cam shaft for releasingthe pawl from said second abutment.

6. In a timing device, a cam shaft, a cam carried by said shaft, a gearon said shaft in lfixed relationship with said cam, said gear havin-g aportion without teeth, a pinion meshing with said gear for driving thesame, a cam follower biased toward said cam, a pawl carried by said camfollower, a stationary abutment in the path of said pawl, said ca-mbeing arranged to move the cam fol-lower to a position in which the pawlis in engaging relationship with the stationary abutment and then torelease the cam follower so that it is now held by the pawl, whereby thepressure of the cam follower is removed from the cam, said gear beingarran-ged to disengage the pinion s-o that the cam shaft stops, meansadvancing said cam shaft to re-engage the gear with the pinion, andmeans operated by said cam shaft for releasing the pawl from thestationary/abutment.

7. In a ytiming device, a slow speed shaft, a high speed shaft meansincluding a pinion and a mutilated gear for driving the high speed shaftthrough one cycle at a time,V

means actuated by the slow speed shaft for advancing the high speedshaft to engage the gear with the pinion to start a new cycle, a camcarried by the high speed shaft, a cam follower biased against said cam,latching means associated with the cam follower and arranged to h-oldthe cam follower off the cam when the cam shaft stops due to themutilated gear disengaging the pinion, and means releasing the latchingmeans after the gear is re-engaged with the pinion.

8. In a control device, a switch panel carrying a switch blade, asliding switch operator member slideably mounted in a direction at anangle to the switch blade for operating the same, a sliding memberadjacent the switch operator and arranged to slide parallel thereto,first spring means biasing the sliding member in one direction, secondspring means biasing the switch operator in the oppostte direction, apawl carried by one of said sliding members and arranged to engage anabutment on the other of said sliding members for causing said slidingmembers to slide together, and means releasing the pawl from saidabutment for permitting relative movement of said sliding members.

9. -In a control device, a switch panel carrying a switch blade, asliding switch operator member slideably mounted in a direction at anangle to the switch -blade for operating the same, -a sliding memberadjacent the switch operator and arranged to slide parallel thereto, apawl carried by one of said sliding members, an abu-tment on the otherof said members, said pawl being arranged to engage said abutment forcausing said sliding members to slide together, and means releasing thepawl from said abutment for permitting relative movement of said slidingmembers.

10. In a control device, a base having a main portion and side portionsforming a channel, a switch panel mounted on said base and supported byone of said side portions, said switch panel being spaced from andparallel with the main portion of the base, an opening in the baseadjacent the panel, switching mechanism carried by said switch panel andextending through said opening in said base, and a switch operatorslideably mounted on the base in the space between the main portion ofthe base and the switch panel, said switch operator being arranged toactuate said switching mechanism.

1.1. In a control device, a base having a main portion and side portionsforming Ia channel, a switch panel mounted on said base and supported byone of said side portions, said switch panel being spaced from andparallel with said main portion of the base, an opening in the baseadjacent said panel, switching mechanism carried by said switch paneland extending through said opening in said base, a switch operatorslideably mounted on the base in the space between the main portion ofthe base and the switch panel, said switch operator being arranged toactuate said switching mechanism, a second operator slideably mountedadjacent said switch operator in said space, and means including meansbetween said operators for causing movement of the operators separatelyor inunison.

12. In a control device, Ia base member, a switch panel mounted on `oneside of said base member, said base member having an opening adjacentsaid switch panel, switching mechanism carried by said switch panel andextending through said opening, a switch operator movably mounted on theside of said base member opposite the switching mechanism and arrangedto actu-ate the same, a pawl cooperating with said switch operator forholding the same in one position, said pawl being mounted on the sameside of the base member as the switch operator, a first actuating meansfor the pawl carried on said one side of the base member, and a seconddetachable actuating means for the pawl, said second actuating meansbeing mounted on the other side of the base member and having a portionextending through the base member to said pawl.

13. In a combination time and condition responsive control, a basemember, a switch panel mounted on said base member, a switch bladecarried by said switch panel, a switch operator movably mounted on oneside of said base member and arranged to actuate said switch blade,timing mechanism moving said switch operator to one position andretaining said switch operator in said one position, said last mentionedmechanism including a pawl which when released allows the switchoperator to return to another position, said pawl being located on thesame side of the base member as the switch operator and closelyadjacentto the base member, time controlled means on said one side of the basemember for releasing said pawl, and condition responsive means on theother side of the base member and having a portion extending to saidpawl for also releasing the same.

14. A device as defined in claim 13 in which the condition responsivemeans is a self contained detachable unit comprising a base mounted onsaid base member, said base carrying 4a responsive element and a lever,said lever having said portion extending to the pawl and another portionextending to the responsive element.

15. In a pressure responsive control unit, a base member, a bellowsattached to said base member, a lever pivoted to `the base member andhaving a portion operated by the bellows, a biasing spring, said leverhaving a second portion arranged to receive said biasing spring at aplurality of points different distances from the lever pivot, anadjusting member Ialso pivoted to the base in a plane generally parallelto said second portions of said lever, said adjusting member alsoincluding a portion generally parallel to the second portion of saidlever and arranged to receive the biasing spring ata plurality ofpoints, and a set screw carried by the base for adjusting the positionof said adjusting member to vary the tension of said spring.

16. A device asdened in claim 13 in which the conditions responsivemeans is a self contained detachable unit comprising a base mounted onsaid base member, an electromagnet including a movable member pivoted tosaid base, said movable member including said portion extending to thepawl.

17. In a timer, a dial member provided with a plurality of slotsextending outwardly from the center thereof, a trip member, a pluralityof pins in said slots, means for retaining the pins in the slots whilepermitting movement thereof from one position to another, said slotsbeing arranged relative to said trip member so that the pins in oneposition travel in a path actuating said trip member, and the pins inanother position travel in a path which does not actuate the trip memberas the dial rotates.

18. In a timer, a dial assembly comprising a pair of plates secured to ahub for rotating .the same, said plates being spaced apart and providedwith a plurality of aligned slots extending outwardly from the hub, laplurality of trip pins in the slots, said pins being provided withenlarged portions in the space between said plates, a trip member, saidslots being arranged relative to the trip member so that the pins in oneposition travel in a path actuating the trip member, Iand the pins inanother position travel in a path which does not actuate the trip memberas the dial assembly rotates,

19. A dial assembly for a timer comprising a pair of plates secured to ahub for supporting and rotating the same, said plates being spaced apartand provided with a plurality of aligned slots extending outwardly fromthe hub, a plurality of trip pins in the slots, said pins being providedwith enlarged portions in the space between the plates, said enlargedportions being slightly shorter than the space between the plates sothat the pins are free to slide in said slots, and spring means locatedbetween said plates for urging said pins toward one end or the other ofsaid slots.

2.0. In a timer, a pair of concentric shafts each carrying an operatingmember, means supporting and rotating said shafts, a dial memberattached to one end of the inner shaft and having a series of slots, apointer carried by the outer shaft behind said dial member and having laportion engaged with the slots for maintaining said dial member andpointer in locked relationship, and a spring located between said shaftsat the other ends thereof arranged to bias the inner shaft rearwardlyrelative to the outer shaft for releasibly holding said dial member andpointer in said locked relationship.

References Cited bythe Examiner UNITED STATES PATENTS 876,416 1/1908Venner et al 200-39 1,456,139 5/1923 Meyer 200-39 1,588,896 5/1926Lensky et al 200-43 1,992,273 2/ 1935 Wilmeth 200-39 2,543,133 2/1951Smith 200-39 X 2,614,375 10/1952 King 172-520 2,695,000 11/1954 Farkaset al l16-135 2,707,932 5/1955 Masciana 116-135 2,816,184 12/1957Manning et al 200-38 2,851,100 9/1958 Good 200-38 X 2,917,939 12/1959Harris 200--38 X 2,960,582 11/1960 Harris 200-38 3,061,701 10/1962Barnett et al 200-33 X 3,094,593 6/1963 Bowman 2004-38 3,139,493 6/ 1964Krieger et al. 200--67 BERNARD A. GILHEANY, Primary Examiner.

ROBERT K. SCHAEFER, Examiner.

H. B. ODONNELL, H. M. FLECK, Assistant Examiners.

1. IN A CONTROL DEVICE, A MOVABLE MEMBER, MEANS BIASING SAID MEMBER INONE DIRECTION, A PAWL CARRIED BY SAID MOVABLE MEMBER, A STATIONARYABUTMENT IN THE PATH OF THE SAID PAWL, DRIVE MEANS FOR MOVING SAIDMOVABLE MEMBER TO A POINT WHERE THE PAWL ENGAGES SAID STATIONARYABUTMENT AND THEN RELEASING THE MOVABLE MEMBER SO THAT THE MOVABLE ISHELD AGAINST ITS BIAS BY THE PAWL ENGAGING SAID STATIONARY ABUTMENT, ACONTROL MEMBER, MEANS BIASING SAID CONTROL MEMBER IN THE DIRECTIONOPPOSITE TO THE BIAS OF THE MOVABLE MEMBER BUT TO LESSER DEGREE, ANABUTMENT CARRIED BY THE CONTROL MEMBER ALSO IN THE PATH OF SAID PAWL ANDENGAGED THEREBY AFTER ITS RELEASE FROM THE STATIONARY ABUTMENT, ANDMEANS RELEASING THE PAWL FIRST FROM THE STATIONARY ABUTMENT AND THENFROM THE CONTROL MEMBER ABUTMENT WHEREBY THE CONTROL MEMBER IS FIRSTMOVED AGAINST ITS BIAS TO ONE POSITION AND IS THEN MOVED BY ITS BIAS TOANOTHER POSITION.